Over-running clutch pulley with increased surface microhardness

ABSTRACT

The over-running clutch pulley ( 10 ) of a preferred embodiment of the invention includes a sheave member ( 20 ), a hub member ( 22 ) located substantially concentrically within the sheave member, and a clutch member ( 24 ), which cooperate to rotationally engage an input device ( 12 ) and an output device ( 14 ). The sheave member preferably includes a sheave input section ( 26 ) adapted to engage the input device, and a sheave clutch section ( 28 ) defining a sheave clutch surface ( 30 ). Similarly, the hub member preferably includes a hub output section ( 32 ) adapted to engage the output device, and a hub clutch section ( 34 ) defining a hub clutch surface ( 36 ). In the preferred embodiment, either the sheave clutch surface, the hub clutch surface, or both, have a surface microhardness greater than the hub output section.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. national phase application ofinternational application No. PCT/US01/17642, filed 31 May 2001, whichclaims priority to U.S. application No. 60/208,244, filed 31 May 2000.

TECHNICAL FIELD

This invention relates generally to devices in the over-running clutchfield, and more specifically to an improved over-running clutch pulleyfor use with an accessory device driven by an automotive engine with abelt drive.

BACKGROUND

During the operation of an automotive engine, a drive belt is typicallyused to power and operate various accessory devices. One of theseaccessory devices is typically an automotive alternator, which provideselectrical power to the automobile. While several arrangements of drivebelts are in use, the serpentine arrangement, which drives severalaccessory devices, is currently most favored. Serpentine arrangementstypically include a drive pulley connected to the crankshaft of theengine (the “output device”) and a drive belt trained about the drivepulley. The drive belt is also trained about one or more conventionaldriven pulleys, which are connected to the input shafts of variousaccessories devices (the “input device”).

Most conventional driven pulleys are made from a one-piece design withno over-running capabilities. In other words, the conventional drivenpulleys are rigidly mounted to the input shaft and are incapable ofallowing relative rotational movement between any section of the drivenpulley and the input shaft. As a result of the lack of any over-runningcapabilities and of the generation of significant inertia by theaccessory, relative slippage between the drive belt and the drivenpulley may occur if the drive belt suddenly decelerates relative to theinput shaft. The relative slippage may cause an audible squeal, which isannoying from an auditory standpoint, and an undue wear on the drivebelt, which is undesirable from a mechanical standpoint.

In a typical driving situation, the drive belt may experience manyinstances of sudden deceleration relative to the input shaft. Thissituation may occur, for example, during a typical shift from first gearto second gear under wide open throttle acceleration. This situation isworsened if the throttle is closed or “back off” immediately after theshift. In these situations, the drive belt decelerates very quicklywhile the driven pulley, with the high inertia from the accessorydevice, maintains a high rotational speed, despite the friction betweenthe drive belt and the driven pulley.

In addition to the instances of sudden deceleration, the drive belt mayexperiences other situations that cause audible vibration and unduewear. As an example, a serpentine arrangement with conventional drivenpulleys may be used with an automobile engine that has an extremely lowidle engine speed (which may increase fuel economy). In thesesituations, the arrangement typically experiences “belt flap” of thedrive belt as the periodic cylinder firing of the automotive enginecauses the arrangement to resonate within a natural frequency and causean audible vibration and an undue wear on the drive belt.

The disadvantage of the conventional driven pulleys, namely the audiblesqueal, the undue wear, and the vibration of the drive belt, may beavoided by the use of an over-running clutch pulley instead of theconventional driven pulley. An over-running clutch pulley allows thepulley to continue to rotate at the same rotational speed and in a samerotational direction after a sudden deceleration of the drive belt. In away, the over-running clutch pulley functions like the rear hub of atypical bicycle; the rear hub and rear wheel of a conventional bicyclecontinue to rotate at the same rotational speed and in the samerotational direction even after a sudden deceleration of the pedals andcrankshaft of the bicycle. An example of an over-running clutch pulleyis described in U.S. Pat. No. 5,598,913 issued to the same assignee ofthis invention and hereby incorporated in its entirety by thisreference.

Since many customers of new automobiles are demanding longer lives, withrelatively fewer repairs, for their new automobiles, there is a need inthe automotive field, if not in other fields, to create an over-runningclutch pulley with increased wear resistance. While forming or treatingthe entire over-running clutch pulley to have a specific surfacemicrohardness will resist wear of the over-running clutch pulley, theseprocesses may increase the costs and, in some cases, the weight of theover-running clutch pulley. This invention provides an over-runningclutch pulley with features intended to increase wear resistance, whileminimizing the costs and weight of the over-running clutch pulley.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an over-running clutch pulley of theinvention, shown with a drive belt as the input device and a cylindricalshaft as the output device;

FIG. 2 is a partial cross-section view, taken along the line 2—2 of FIG.1, of the over-running clutch pulley of a first preferred embodiment;

FIG. 3 is a partial cross-section view, similar to FIG. 2, of theover-running clutch pulley of a second preferred embodiment; and

FIG. 4 is a partial cross-section view, similar to FIG. 2, of theover-running clutch pulley of a third preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of three preferred embodiments of theinvention is not intended to limit the scope of this invention to thesepreferred embodiments, but rather to enable any person skilled in theart of over-running clutches to make and use this invention.

As shown in FIG. 1, the invention includes an over-running clutch pulley10 for rotationally engaging an input device 12 and an output device 14.The over-running clutch pulley 10 has been designed for use with a drivebelt 16 as the input device 12, and with a cylindrical shaft 18 as theoutput device 14. More specifically, the over-running clutch pulley 10has been particularly designed for use with a drive belt 16 with agrooved surface and a cylindrical shaft 18 of an automotive alternator.The over-running clutch pulley 10 may be used, however, in otherenvironments, with other suitable input devices, such as smooth belt, atoothed belt, a V-shaped belt, or even a toothed gear, and with othersuitable output devices, such as a polygonal shaft. Furthermore, theover-running clutch pulley 10 may be used in an environment with twodevices that alternate their rotational input responsibilities, and inan environment with an “output device” that actually provides rotationalinput and with an “input device” that actually receives rotationalinput. In these alternative embodiments, the terms “input device” and“output device” are interchangeable.

As shown in FIG. 2, the over-running clutch pulley 10 of the preferredembodiment includes a sheave member 20, a hub member 22 locatedsubstantially concentrically within the sheave member 20, and a clutchmember 24, which cooperate to rotationally engage the drive belt and thecylindrical shaft. The sheave member 20 preferably includes a sheaveinput section 26 adapted to the engage the input device, and a sheaveclutch section 28 defining a sheave clutch surface 30. Similarly, thehub member 22 preferably includes a hub output section 32 adapted toengage the output device, and a hub clutch section 34 defining a hubclutch surface 36. In the preferred embodiment, either the sheave clutchsurface 30, the hub clutch surface 36, or both, have a surfacemicrohardness greater than the hub output section 32, which increasewear resistance for the over-running clutch pulley 10, while minimizingcost and weight. The over-running clutch pulley of alternativeembodiments may include other elements, such as a sealing member tosubstantially prevent passage of dirt into and grease out of theover-running clutch pulley, or any other suitable elements that do notsubstantially interfere with the functions of the sheave member, the hubmember, and the clutch member.

The sheave input section 26 of the sheave member 20 of the preferredembodiment functions to engage the drive belt. To substantially preventrotational and axial slippage of the sheave member 20 and the drivebelt, the sheave input section 26 preferably defines a sheave inputsurface 38 with two sheave input shoulders 40 and at least one sheaveinput groove 42. The sheave input section 26 may alternatively defineother suitable surfaces, such as toothed surfaces or ribbed surfaces, toengage the input device. The sheave input surface 38 is preferablyoutwardly directed (away from the rotational axis of the over-runningclutch pulley 10) and is preferably substantially cylindrically shaped.The sheave input section 26 is preferably made from conventionalstructural materials, such as steel, and with conventional methods, butmay alternatively be made from other suitable materials (as describedbelow) and from other suitable methods.

The hub output section 32 of the hub member 22 of the preferredembodiment functions to engage the cylindrical shaft. The hub outputsection 32 preferably defines a hub output surface 44 with a smoothsection (which functions to ease and center the assembly of theover-running clutch pulley 10 onto the cylindrical shaft), a threadedsection 45 (which functions to substantially prevent rotation and toaxially retain the hub member 22 to the cylindrical shaft), and ahexagonal section (which functions to mate with an alien wrench for easytightening and loosening of the over-running clutch pulley 10 onto andoff of the cylindrical shaft). Of course, the hub output section 32 mayinclude other suitable devices or define other surfaces to preventrotational and axial slippage, to engage the cylindrical shaft, and toengage a tool for tightening or loosening the over-running clutch pulley10 onto and off of the cylindrical shaft. The hub output surface 44 ispreferably inwardly directed (toward the rotational axis of theover-running clutch pulley 10) and is preferably substantiallycylindrically shaped. The hub output section 32 is preferably made fromconventional structural materials, such as steel, and with conventionalmethods, but may alternatively be made from other suitable materials (asdescribed below) and from other suitable methods.

The over-running clutch pulley 10 of the preferred embodiment alsoincludes a bearing member 46, which functions to allow relativerotational movement of the sheave member 20 and the hub member 22. Thebearing member 46, which is preferably a rolling element type,preferably includes an outer race element 48 preferably press-fitmounted on the sheave member 20, an inner race element 50 preferablypress-fit mounted on the hub member 22, ball bearing elements 52preferably located between the outer race element 48 and the inner raceelement 50, and bearing seals 53 preferably extending between the outerrace element 48 and the inner race element 50 on either side of the ballbearing elements 52. The bearing member 46 may alternatively be of othersuitable types, such as a journal bearing or a roller bearing, mayalternatively include other suitable elements, and may alternatively bemounted in other suitable manners. The bearing member 46 is aconventional device and, as such, is preferably made from conventionalmaterials and with conventional methods, but may alternatively be madefrom other suitable materials and with other suitable methods.

The sheave clutch section 28 and the hub clutch section 34 of thepreferred embodiment function to provide the sheave clutch surface 30and the hub clutch surface 36, respectively, for the engagement with theclutch member 24. The sheave clutch section 28 preferably extendsradially inward from the sheave member 20. In this manner, the sheaveclutch section 28 is preferably made from the same material and with thesame methods as the sheave input section 26, but may alternatively bemade from other suitable materials and with other suitable methods (asdescribed below). The hub clutch section 34 preferably extends radiallyoutward from and axially over the hub output section 32. In this manner,the hub clutch section 34 is preferably made from the same material andwith the same methods as the hub output section 32, but mayalternatively be made from other suitable materials and with othersuitable methods (as described below). The hub clutch section 34preferably partially defines a closed clutch cavity 54 to contain theclutch member 24.

In the preferred embodiment, the sheave clutch surface 30 and the hubclutch surface 36 are located substantially adjacent with an axial gap56 between each other. The sheave clutch surface 30 and the hub clutchsurface 36 are preferably inwardly directed (toward the rotational axisof the over-running clutch pulley 10) and are preferably substantiallycylindrically shaped. Furthermore, the sheave clutch surface 30 and thehub clutch surface 36 preferably have a similar radial diameter, asimilar axial length, and a similar smooth finish. These features allowoptimum performance of the clutch member 24. The sheave clutch surface30 and the hub clutch surface 36 may alternatively have differences witheach other on these, or other, design specifications.

The clutch member 24 of the preferred embodiment functions to engage thesheave clutch surface 30 and the hub clutch surface 36 upon theacceleration of the sheave member 20 in a first rotational directionrelative to the hub member 22, and to disengage the sheave clutchsurface 30 and the hub clutch surface 36 upon the deceleration of thesheave member 20 in the first rotational direction relative to the hubmember 22. In the preferred embodiment, the clutch member 24 is a coilspring 58. The coil spring 58, which is made from conventional materialsand with conventional methods, accomplishes the above features by theparticular size and orientation of the coil spring 58 within the closedclutch cavity 54. In alternative embodiments, the clutch member 24 mayinclude other suitable devices that accomplish the above features.

The coil spring 58 is preferably designed with a relaxed spring radialdiameter that is sized slightly greater than an inner diameter of thesheave clutch surface 30 and the hub clutch surface 36. Thus, wheninserted into the closed clutch cavity 54 and when experiencing norotational movement of the sheave member 20 or the hub member 22, thecoil spring 58 frictionally engages with and exerts an outward force onboth the sheave clutch surface 30 and the hub clutch surface 36.Further, the coil spring 58 is preferably oriented within the closedclutch cavity 54 such that the coils extend axially in the firstrotational direction from the sheave clutch surface 30 to the hub clutchsurface 36. With this orientation, relative rotational movement of thesheave member 20 and the hub member 22 will result in an unwinding orwinding of the spring member. In other words, acceleration of the sheavemember 20 in the first rotational direction relative to the hub member22 will bias an unwinding of the coil spring 58 and deceleration of thesheave member 20 in the first rotational direction relative to the hubmember 22 will bias a winding of the coil spring 58.

The unwinding of the coil spring 58 tends to increase the outward forceof the coil spring 58 on the sheave clutch surface 30 and the hub clutchsurface 36, thereby providing engagement, or “lock”, of the sheavemember 20 and the hub member 22. This engagement condition preferablyoccurs upon the acceleration of the sheave member 20 in the firstrotational direction relative to the hub member 22. On the other hand,the winding of the coil spring 58 tends to decrease the outward force ofthe coil spring 58 on the sheave clutch surface 30 and the hub clutchsurface 36, thereby allowing disengagement, or “slip”, of the sheavemember 20 and the hub member 22. This disengagement condition preferablyoccurs upon the deceleration of the sheave member 20 in the firstrotational direction relative to the hub member 22.

During the “slip” condition of the over-running clutch pulley 10, thecoil spring 58 will lightly rub across the sheave clutch surface 30 orthe hub clutch surface 36, which may cause wear of these surfaces.Similarly, during the “lock” condition of the over-running clutch pulley10, the coil spring 58 will forcefully engage with the sheave clutchsurface 30 and the hub clutch surface 36, which may also cause wear ofthese surfaces. To resist the wear of these surfaces; the sheave clutchsurface 30 and the hub clutch surface 36 are preferably formed ortreated to have a sufficient surface microhardness value.

The term “surface microhardness” refers to a surface property aspreferably measured by the Rockwell Hardness ‘C’ standard. In somecases, however, the surface may be treated or coated and a measurementunder the Rockwell Hardness ‘C’ standard will “puncture” through thetreatment or coating. In these cases, the surface microhardness value ispreferably measured at ½ the distance of the surface treatment orcoating.

Since the rest of the over-running clutch pulley 10 does not have to beformed or treated to have such surface microhardness, the sheave clutchsurface 30 and the hub clutch surface 36 preferably have an increasedsurface microhardness relative to the rest of the over-running clutchpulley 10. More specifically, the sheave clutch surface 30 and the hubclutch surface 36 preferably have a surface microhardness greater thanthe hub output section 32, and equivalent to or greater than 50 RockwellHardness ‘C’(“R_(c)”). This specific surface microhardness resists wearof the over-running clutch pulley 10, while the difference between thesurface microhardness of theses surfaces and the rest of theover-running clutch pulley 10 reduces costs and, in some cases, reducesweight. Although the preferred embodiments describe an increased surfacemicrohardness of the sheave clutch surface 30 and the hub clutch surface36, alternative embodiments may include an increased microhardness ofonly one of the sheave clutch surface 30 and the hub clutch surface 36.

The increased surface microhardness may be accomplished with severaldifferent structures and methods. In the first preferred embodiment ofthe invention, the increase is accomplished by treating the sheaveclutch surface 30 of the sheave clutch section 28 and the hub clutchsurface 36 of the hub clutch section 34. The treatment preferablyincludes diffusing carbon into the sheave clutch surface 30 and the hubclutch surface 36. This preferred treatment, commonly known ascarburizing, is well known in the metallurgical field. The increasedsurface microhardness may alternatively be accomplished by othersuitable treatments, either in combination with or as substitution forthe preferred treatment. These other suitable methods may includecarbonitriding (similar to carburizing, except for the small addition ofnitrogen in the atmosphere and the small reduction in temperature),induction heat treatment, radiant heat treatment, laser cladding, andchemical or electroplating deposition. The use of the preferredtreatment preferably provides the sheave clutch surface 30 and the hubclutch surface 36 having a surface microhardness greater than the huboutput section 32, and equivalent to or greater than 50 R_(c).

As shown in FIG. 3, the increased surface microhardness is accomplishedin the over-running clutch pulley 10′ of the second preferred embodimentby separately forming and later connecting the hub clutch section 34′and the hub output section 32′. The hub clutch section 34′ may betreated using a suitable method, such as carbonitriding, while the huboutput section 32′ may be left untreated. The hub clutch section 34′ ispreferably connected to the hub output section 32′ with a mechanicalfastener (not shown), but may alternatively be connected with any othersuitable device or method. The use of this method preferably providesthe hub clutch surface 36 having a surface microhardness greater thanthe hub output section 32′, and equivalent to or greater than 50 R_(c).Although the second preferred embodiment only describes the two-piecenature of the hub clutch section 34′ and the hub output section 32′, analternative embodiment of the invention may include separately formingand later connecting the sheave clutch section 28 and the sheave inputsection 26.

As shown in FIG. 4, the increased surface microhardness is accomplishedin the over-running clutch pulley 10″ of the third preferred embodimentby separately forming and later connecting the sheave clutch surface 30″and the sheave clutch section 28, and by separately forming and laterconnecting the hub clutch surface 36″ and the hub clutch section 34.Like the method of the second preferred embodiment, the sheave clutchsurface 30″ and the hub clutch surface 36″ may be treated using asuitable method, such as carbonitriding, while the remaining portions ofthe sheave clutch section 28 and the hub clutch section 34 may be leftuntreated. In this embodiment, however, the sheave clutch surface 30″and the hub clutch surface 36″ are preferably made from a metallicmaterial, such as steel, while the remaining portions of the sheaveclutch section 28, the sheave input section 26, the hub clutch section34, and the hub output section 32 are preferably made from anon-hardened steel, or even a non-metallic material. The sheave clutchsurface 30″ and the hub clutch surface 36″ are preferably coupled to thesheave clutch section 28 and the hub clutch section 34 by a press fitarrangement, but may alternatively be connected with adhesive bonds,mechanical fasteners, molding processes, or any other suitable device ormethod. In the third preferred embodiment, the sheave clutch surface 30″and the hub clutch surface 36″ are made from steel, while the remainingportions are made from plastic. In alternative embodiments, however, thesheave clutch surface 30″ and the hub clutch surface 36″ may be madefrom any suitable material such that they have a surface microhardnessgreater than the hub output section 32 of the hub member 22, andequivalent to or greater than 50 R_(c).

As shown in FIG. 2, to insure the proper placement of the spring memberwithin the closed clutch cavity 54, the sheave member 20 of thepreferred embodiment includes a sheave collar section 60 defining asheave collar surface 62, and the hub clutch section 34 of the preferredembodiment defines a hub flange surface 64. The sheave collar section 60preferably extends radially inward from the sheave input section 26 andadjacent the sheave clutch section 28. The sheave collar surface 62 andthe hub flange surface 64 are preferably located on opposite ends of theclosed clutch cavity 54. In this manner, the sheave collar surface 62and the hub flange surface 64 cooperate with the sheave clutch surface30 and the hub clutch surface 36 to actually define the closed clutchcavity 54. The over-running clutch pulley 10 of the preferred embodimentmay, of course, use other suitable devices to insure the properplacement of the spring member within the closed clutch cavity 54. Thesedevices may be surfaces defined by other sections of the sheave member20 or the hub member 22, or surfaces defined by other suitable elements.In the same manner as the sheave clutch surface 30 and the hub clutchsurface 36, the sheave collar surface 62 and the hub flange surface 64preferably have a surface microhardness greater than the hub outputsection 32, and equivalent to or greater than 50 R_(c). This increasedsurface microhardness, which further resists wear of the over-runningclutch pulley 10, are preferably accomplished by one of the structuresand methods as described above for the sheave clutch surface 30 and thehub clutch surface 36, but may alternatively be accomplished by anyother suitable structure or method.

As any person skilled in the art of over-running clutches will recognizefrom the previous detailed description and from the figures and claims,modifications and changes can be made to the preferred embodiments ofthe invention without departing from the scope of this invention definedin the following claims.

1. An over-running clutch pulley for rotationally engaging an input device and an output device, comprising: a sheave member including a sheave input section, a sheave clutch section and sheave clutch surface, the sheave input section adapted to the engage the input device, said sheave input section and said sheave clutch section being unitarily formed together as one piece; a hub member located substantially concentrically within said sheave member and including a hub output section, a hub clutch section and a hub clutch surface, the hub output section adapted to engage the output device, the hub clutch surface being located substantially adjacent said sheave clutch surface, said hub output section and said hub clutch section being unitarily formed together as one piece; a clutch member adapted to engage said sheave clutch surface and said hub clutch surface upon the acceleration of said sheave member in a first rotational direction relative to said hub member, and to disengage said sheave clutch surface and said hub clutch surface upon the deceleration of said sheave member in the first rotational direction relative to said hub member; wherein one of said sheave clutch surface and said hub clutch surface is a surface having diffused carbon therein and has a surface microhardness greater than said hub output section.
 2. The over-running clutch pulley of claim 1 wherein said sheave input section defines a sheave input surface with two sheave shoulders and at least one sheave input groove that cooperate to engage a drive belt as the input device and to substantially prevent rotational and axial slippage between said sheave input surface and the drive belt.
 3. The over-running clutch pulley of claim 1 wherein said sheave clutch surface has a surface microhardness greater than said hub output section.
 4. The over-running clutch pulley of claim 3 wherein said sheave clutch surface has a surface microhardness value equivalent to or greater than 50 R_(C).
 5. The over-running clutch pulley of claim 3 wherein said sheave clutch surface is inwardly directed and substantially cylindrically shaped.
 6. The over-running clutch pulley of claim 1 wherein said sheave clutch surface is defined by an insert and said sheave input section is made from a non-metallic material.
 7. The over-running clutch pulley of claim 1 wherein said sheave member further includes a sheave collar section defining a sheave collar surface having a surface microhardness greater than said hub output section, and wherein said sheave clutch section and said sheave collar section cooperate to substantially define a clutch cavity adapted to contain said clutch member.
 8. The over-running clutch pulley of claim 7 wherein said sheave collar surface has a surface microhardness value equivalent to or greater than 50 R_(C).
 9. The over-running clutch pulley of claim 1 further comprising a bearing member located between said sheave member and said hub member, and adapted to allow relative rotational movement of said sheave member and said hub member.
 10. The over-running clutch pulley of claim 1 wherein said hub output section defines a hub output surface adapted to engage a cylindrical shaft as the output device.
 11. The over-running clutch pulley of claim 10 wherein said hub clutch surface has a surface microhardness value equivalent to or greater than 50 R_(C).
 12. The over-running clutch pulley of claim 10 wherein said hub clutch surface is inwardly directed and substantially cylindrically shaped.
 13. The over-running clutch pulley of claim 1 wherein said hub clutch surface has a surface microhardness greater than said hub output section.
 14. The over-running clutch pulley of claim 1 wherein said hub clutch section is made from a metallic material.
 15. The over-running clutch pulley of claim 1 wherein said hub clutch surface is defined by an insert and said hub output section is made from a non-metallic material.
 16. The over-running clutch pulley of claim 1 wherein said hub clutch section further defines a hub flange surface having a surface microhardness greater than said hub output section, and wherein said hub clutch surface and said hub flange surface cooperate to substantially define a clutch cavity adapted to contain said clutch member.
 17. The over-running clutch pulley of claim 16 wherein said hub flange surface has a surface microhardness value equivalent to or greater than 50 R_(C).
 18. A method of manufacturing an over-running clutch pulley for rotationally engaging an input device and an output device, comprising: providing a sheave member including a sheave input section and a sheave clutch section and a sheave clutch surface, the sheave input section and the sheave clutch section being unitarily formed as one piece; and adapting the sheave input section to the engage the input device; providing a hub member including a hub output section and a hub clutch section defining a hub clutch surface, the hub clutch section and hub output section being unitarily formed as one piece; adapting the hub output section to engage the output device; surface treating by diffusing carbon into the surface of one of the sheave clutch surface and the hub clutch surface to have a surface microhardness greater than the hub output section; locating the hub member substantially concentrically within the sheave member and the sheave clutch surface substantially adjacent the hub clutch surface; and providing a clutch member; and adapting the clutch member to engage the sheave clutch surface and the hub clutch surface upon the acceleration of the sheave member in a first rotational direction relative to the hub member, and to disengage the sheave clutch surface and the hub clutch surface upon the deceleration of the sheave member in the first rotational direction relative to the hub member.
 19. The method of claim 18 further comprising treating the sheave clutch surface to have a surface microhardness greater than the hub output section.
 20. The method of claim 19 further comprising treating the sheave clutch surface to have a surface microhardness value equivalent to or greater than 50 R_(C).
 21. The method of claim 18 further comprising treating the hub clutch surface to have a surface microhardness greater than the hub output section.
 22. The method of claim 21 further comprising treating the hub clutch surface to have a surface microhardness value equivalent to or greater than 50 R_(C). 